eJournals International Colloquium Tribology 23/1

International Colloquium Tribology
ict
expert verlag Tübingen
125
2022
231

Improving Microbial Control Without Excess Reserve Alkalinity in Metalworking Fluid Formulations

125
2022
Harish Potnis
Clayton Cooper
ict2310093
23rd International Colloquium Tribology - January 2022 93 Improving Microbial Control Without Excess Reserve Alkalinity in Metalworking Fluid Formulations Harish Potnis ANGUS Chemical Company, Buffalo Grove, USA Clayton Cooper ANGUS Chemical Company, Buffalo Grove, USA 1. Introduction Over the course of the history of metalworking fluids formulations, amines have played a vital role in providing key performance attributes and helping drive a variety of innovations in a fluid design. However, selecting the right combination of „basic“and „complimentary amines“ remains one of the more complex challenges for today’s formulators. Today, by using the right combination of basic and specialty / complimentary amines, formulators can reserve the alkalinity of a metalworking fluid formulation and maintain expected performance without excess buffering. Most high-quality amines can eliminate the requirement of reserve alkalinity and help improve a formulation’s resistance to microbial growth (due to their branched structure), as well as provide improved corrosion control in iron / steel in multi-metal fluids and enhanced pH. Below is the guideline formulation and an overview of the amines evaluated by ANGUS Chemical Company. 2. Alkalinity vs. Microbial Studies This lab study investigates the relation of fluid life to reserve alkalinity throughout different amine combinations. Base amines (without TEA) include AB / AEPD, 4A, MIPA, DGA, MEA and their impact on fluid life. AB / AEPD shows exceptional fluid life of over 13 weeks (using ANGUS-modified ASTM E2275) at relatively low alkalinity levels. (refer to picture 1) 94 23rd International Colloquium Tribology - January 2022 Improving Microbial Control Without Excess Reserve Alkalinity in Metalworking Fluid Formulations (Picture 1) When the base amine formulas were combined with TEA (which raises the alkalinity), the results show that fluid life is independent of reserve alkalinity. This is contrary to the conceptthat adding TEA to increase reserve alkalinity will result in increased fluid life. When all base amines are combined with BAE (butylaminoethanol), we still see better results with AB / AEPD at relatively low reserve alkalinity levels. Furthermore, we combined all base amines with the unique amine chemistry of 3A4O (3-amino-4-octanol), and observed excellent results when combined with AB / AEPD. This improvement was not exclusive to AB / AEPD, however, as all base amines were improved significantly with the addition of 3A4O. As a result, we observe again that the proper selection of amine combination will bring a positive impact in overall fluid performance. Our corrosion resistance studies were conducted using the IP-287 method with cast iron chips. We focused on all of the base amine formulations as well as those in combination with TEA at a dilution of 2.5% in tap water. (refer to picture 2) (Picture 2) It can be clearly observed that among the base amine formulations without TEA, AB / AEPD performed the best while all other amines showed corrosion. Combing these formulations with 10% TEA was sufficient in protecting against all corrosion at 2.5%, however, this performance was achieved when using AB / AEPD alone. 3. Conclusion Through the results of our analysis, we can conclude that alkalinity does not always help to improve fluid longevity and formulations can be made without excessive alkalinity. Formulators can achieve better corrosion control properties with TEA, but must compromise on other properties such as Al staining, Co and Cu leaching. AB / AEPD can be an excellent choice to achieve synergistic effects of both base amine and complementary amines, and adding 3A4O (3-amino-4-octanol) into existing metalworking fluid formulations can boost overall performance.